Fix for PR #536. Our lock routines allow locking the address zero, so in the case of synchronized statements we have to explicitly check for that if we're relying on the MMU traps to cause NullPointerException's.
Fix for PR #536. Our lock routines allow locking the address zero, so
in the case of synchronized statements we have to explicitly check for
that if we're relying on the MMU traps to cause NullPointerException's.

In these cases, make an explicit reference to *addr in _lockMutex()
and _unlockMutex() which will cause a trap.

kaffe/kaffe,kaffe/kaffe,kaffe/kaffe,kaffe/kaffe,kaffe/kaffe